1 /*
2 * Cryptographic API.
3 *
4 * HMAC: Keyed-Hashing for Message Authentication (RFC2104).
5 *
6 * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
7 * Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au>
8 *
9 * The HMAC implementation is derived from USAGI.
10 * Copyright (c) 2002 Kazunori Miyazawa <miyazawa@linux-ipv6.org> / USAGI
11 *
12 * This program is free software; you can redistribute it and/or modify it
13 * under the terms of the GNU General Public License as published by the Free
14 * Software Foundation; either version 2 of the License, or (at your option)
15 * any later version.
16 *
17 */
18
19 #include <crypto/hmac.h>
20 #include <crypto/internal/hash.h>
21 #include <crypto/scatterwalk.h>
22 #include <linux/err.h>
23 #include <linux/init.h>
24 #include <linux/kernel.h>
25 #include <linux/module.h>
26 #include <linux/scatterlist.h>
27 #include <linux/string.h>
28
29 struct hmac_ctx {
30 struct crypto_shash *hash;
31 };
32
align_ptr(void * p,unsigned int align)33 static inline void *align_ptr(void *p, unsigned int align)
34 {
35 return (void *)ALIGN((unsigned long)p, align);
36 }
37
hmac_ctx(struct crypto_shash * tfm)38 static inline struct hmac_ctx *hmac_ctx(struct crypto_shash *tfm)
39 {
40 return align_ptr(crypto_shash_ctx_aligned(tfm) +
41 crypto_shash_statesize(tfm) * 2,
42 crypto_tfm_ctx_alignment());
43 }
44
hmac_setkey(struct crypto_shash * parent,const u8 * inkey,unsigned int keylen)45 static int hmac_setkey(struct crypto_shash *parent,
46 const u8 *inkey, unsigned int keylen)
47 {
48 int bs = crypto_shash_blocksize(parent);
49 int ds = crypto_shash_digestsize(parent);
50 int ss = crypto_shash_statesize(parent);
51 char *ipad = crypto_shash_ctx_aligned(parent);
52 char *opad = ipad + ss;
53 struct hmac_ctx *ctx = align_ptr(opad + ss,
54 crypto_tfm_ctx_alignment());
55 struct crypto_shash *hash = ctx->hash;
56 SHASH_DESC_ON_STACK(shash, hash);
57 unsigned int i;
58
59 shash->tfm = hash;
60 shash->flags = crypto_shash_get_flags(parent)
61 & CRYPTO_TFM_REQ_MAY_SLEEP;
62
63 if (keylen > bs) {
64 int err;
65
66 err = crypto_shash_digest(shash, inkey, keylen, ipad);
67 if (err)
68 return err;
69
70 keylen = ds;
71 } else
72 memcpy(ipad, inkey, keylen);
73
74 memset(ipad + keylen, 0, bs - keylen);
75 memcpy(opad, ipad, bs);
76
77 for (i = 0; i < bs; i++) {
78 ipad[i] ^= HMAC_IPAD_VALUE;
79 opad[i] ^= HMAC_OPAD_VALUE;
80 }
81
82 return crypto_shash_init(shash) ?:
83 crypto_shash_update(shash, ipad, bs) ?:
84 crypto_shash_export(shash, ipad) ?:
85 crypto_shash_init(shash) ?:
86 crypto_shash_update(shash, opad, bs) ?:
87 crypto_shash_export(shash, opad);
88 }
89
hmac_export(struct shash_desc * pdesc,void * out)90 static int hmac_export(struct shash_desc *pdesc, void *out)
91 {
92 struct shash_desc *desc = shash_desc_ctx(pdesc);
93
94 desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;
95
96 return crypto_shash_export(desc, out);
97 }
98
hmac_import(struct shash_desc * pdesc,const void * in)99 static int hmac_import(struct shash_desc *pdesc, const void *in)
100 {
101 struct shash_desc *desc = shash_desc_ctx(pdesc);
102 struct hmac_ctx *ctx = hmac_ctx(pdesc->tfm);
103
104 desc->tfm = ctx->hash;
105 desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;
106
107 return crypto_shash_import(desc, in);
108 }
109
hmac_init(struct shash_desc * pdesc)110 static int hmac_init(struct shash_desc *pdesc)
111 {
112 return hmac_import(pdesc, crypto_shash_ctx_aligned(pdesc->tfm));
113 }
114
hmac_update(struct shash_desc * pdesc,const u8 * data,unsigned int nbytes)115 static int hmac_update(struct shash_desc *pdesc,
116 const u8 *data, unsigned int nbytes)
117 {
118 struct shash_desc *desc = shash_desc_ctx(pdesc);
119
120 desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;
121
122 return crypto_shash_update(desc, data, nbytes);
123 }
124
hmac_final(struct shash_desc * pdesc,u8 * out)125 static int hmac_final(struct shash_desc *pdesc, u8 *out)
126 {
127 struct crypto_shash *parent = pdesc->tfm;
128 int ds = crypto_shash_digestsize(parent);
129 int ss = crypto_shash_statesize(parent);
130 char *opad = crypto_shash_ctx_aligned(parent) + ss;
131 struct shash_desc *desc = shash_desc_ctx(pdesc);
132
133 desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;
134
135 return crypto_shash_final(desc, out) ?:
136 crypto_shash_import(desc, opad) ?:
137 crypto_shash_finup(desc, out, ds, out);
138 }
139
hmac_finup(struct shash_desc * pdesc,const u8 * data,unsigned int nbytes,u8 * out)140 static int hmac_finup(struct shash_desc *pdesc, const u8 *data,
141 unsigned int nbytes, u8 *out)
142 {
143
144 struct crypto_shash *parent = pdesc->tfm;
145 int ds = crypto_shash_digestsize(parent);
146 int ss = crypto_shash_statesize(parent);
147 char *opad = crypto_shash_ctx_aligned(parent) + ss;
148 struct shash_desc *desc = shash_desc_ctx(pdesc);
149
150 desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;
151
152 return crypto_shash_finup(desc, data, nbytes, out) ?:
153 crypto_shash_import(desc, opad) ?:
154 crypto_shash_finup(desc, out, ds, out);
155 }
156
hmac_init_tfm(struct crypto_tfm * tfm)157 static int hmac_init_tfm(struct crypto_tfm *tfm)
158 {
159 struct crypto_shash *parent = __crypto_shash_cast(tfm);
160 struct crypto_shash *hash;
161 struct crypto_instance *inst = (void *)tfm->__crt_alg;
162 struct crypto_shash_spawn *spawn = crypto_instance_ctx(inst);
163 struct hmac_ctx *ctx = hmac_ctx(parent);
164
165 hash = crypto_spawn_shash(spawn);
166 if (IS_ERR(hash))
167 return PTR_ERR(hash);
168
169 parent->descsize = sizeof(struct shash_desc) +
170 crypto_shash_descsize(hash);
171
172 ctx->hash = hash;
173 return 0;
174 }
175
hmac_exit_tfm(struct crypto_tfm * tfm)176 static void hmac_exit_tfm(struct crypto_tfm *tfm)
177 {
178 struct hmac_ctx *ctx = hmac_ctx(__crypto_shash_cast(tfm));
179 crypto_free_shash(ctx->hash);
180 }
181
hmac_create(struct crypto_template * tmpl,struct rtattr ** tb)182 static int hmac_create(struct crypto_template *tmpl, struct rtattr **tb)
183 {
184 struct shash_instance *inst;
185 struct crypto_alg *alg;
186 struct shash_alg *salg;
187 int err;
188 int ds;
189 int ss;
190
191 err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SHASH);
192 if (err)
193 return err;
194
195 salg = shash_attr_alg(tb[1], 0, 0);
196 if (IS_ERR(salg))
197 return PTR_ERR(salg);
198 alg = &salg->base;
199
200 /* The underlying hash algorithm must be unkeyed */
201 err = -EINVAL;
202 if (crypto_shash_alg_has_setkey(salg))
203 goto out_put_alg;
204
205 ds = salg->digestsize;
206 ss = salg->statesize;
207 if (ds > alg->cra_blocksize ||
208 ss < alg->cra_blocksize)
209 goto out_put_alg;
210
211 inst = shash_alloc_instance("hmac", alg);
212 err = PTR_ERR(inst);
213 if (IS_ERR(inst))
214 goto out_put_alg;
215
216 err = crypto_init_shash_spawn(shash_instance_ctx(inst), salg,
217 shash_crypto_instance(inst));
218 if (err)
219 goto out_free_inst;
220
221 inst->alg.base.cra_priority = alg->cra_priority;
222 inst->alg.base.cra_blocksize = alg->cra_blocksize;
223 inst->alg.base.cra_alignmask = alg->cra_alignmask;
224
225 ss = ALIGN(ss, alg->cra_alignmask + 1);
226 inst->alg.digestsize = ds;
227 inst->alg.statesize = ss;
228
229 inst->alg.base.cra_ctxsize = sizeof(struct hmac_ctx) +
230 ALIGN(ss * 2, crypto_tfm_ctx_alignment());
231
232 inst->alg.base.cra_init = hmac_init_tfm;
233 inst->alg.base.cra_exit = hmac_exit_tfm;
234
235 inst->alg.init = hmac_init;
236 inst->alg.update = hmac_update;
237 inst->alg.final = hmac_final;
238 inst->alg.finup = hmac_finup;
239 inst->alg.export = hmac_export;
240 inst->alg.import = hmac_import;
241 inst->alg.setkey = hmac_setkey;
242
243 err = shash_register_instance(tmpl, inst);
244 if (err) {
245 out_free_inst:
246 shash_free_instance(shash_crypto_instance(inst));
247 }
248
249 out_put_alg:
250 crypto_mod_put(alg);
251 return err;
252 }
253
254 static struct crypto_template hmac_tmpl = {
255 .name = "hmac",
256 .create = hmac_create,
257 .free = shash_free_instance,
258 .module = THIS_MODULE,
259 };
260
hmac_module_init(void)261 static int __init hmac_module_init(void)
262 {
263 return crypto_register_template(&hmac_tmpl);
264 }
265
hmac_module_exit(void)266 static void __exit hmac_module_exit(void)
267 {
268 crypto_unregister_template(&hmac_tmpl);
269 }
270
271 module_init(hmac_module_init);
272 module_exit(hmac_module_exit);
273
274 MODULE_LICENSE("GPL");
275 MODULE_DESCRIPTION("HMAC hash algorithm");
276 MODULE_ALIAS_CRYPTO("hmac");
277
